The present invention relates to semiconductor devices and manufacturing methods thereof, and more particularly to a technique that can be suitably applied to a method for manufacturing a semiconductor device including, for example, a solid-state imaging element.
Solid-state imaging elements using a complementary metal oxide semiconductor (CMOS), namely the so-called “CMOS image sensors” have been developed as a typical solid-state imaging element. The CMOS image sensor includes a plurality of pixels, each having a photodiode and a transfer transistor.
Japanese Unexamined Patent Application Publication No. 2010-161236 (Patent Document 1) discloses the invention which relates to a manufacturing method of a photoelectric converter that reduces an etching damage to a photoelectric conversion portion, thereby improving the accuracy of control of an offset in a protective region of the photoelectric conversion portion.
Japanese Translation of PCT International Application Publication No. JP-T-2009-506542 (Patent Document 2) discloses the invention in which a gate oxynitride film having a thickness twice that of a general gate oxynitride film is provided over a photosensitive region of a CMOS imager to reduce the reflection of photons on a surface of a photosensor, resulting in reduction of dark current.